Two decades after 2003 invasion, US military exits its final bases in Iraq

United States forces are completing their withdrawal from their remaining bases in Iraq on September 30, ending a military presence that began with the 2003 invasion, paused after the 2011 withdrawal and resumed in 2014 when Islamic State seized large areas of Iraq and Syria. The departure was agreed by Washington and Baghdad in 2024 under President Joe Biden and is being implemented by President Donald Trump’s administration even as the United States remains engaged in a wider war with Iran.

The withdrawal is widely welcomed in Iraq as a restoration of sovereignty, but it also changes the country’s fragile security balance. Iranian-aligned groups are portraying the departure as a strategic victory, while some Iraqi and Kurdish security officials warn that reduced US intelligence, logistics and drone support could create space for Islamic State sleeper cells to rebuild. Those concerns represent assessments by security officials rather than evidence that a major ISIS resurgence is inevitable.

Why are US troops finally leaving Iraq on September 30 after returning in 2014?

American forces initially entered Iraq in March 2003 during the invasion that removed Saddam Hussein. Following years of occupation and counterinsurgency fighting, US troops withdrew at the end of 2011, only to return less than three years later after Islamic State captured Mosul and established control across large parts of Iraq and Syria.

The US-led coalition then supported Iraqi forces through intelligence, air power, training and logistics as Baghdad retook territory from the group. Islamic State’s territorial caliphate was largely defeated by 2017, gradually changing the rationale for maintaining thousands of foreign troops inside Iraq.

Washington and Baghdad ultimately agreed in 2024 on a phased transition away from the coalition mission. The United States and Iraq described the arrangement as a move toward a conventional bilateral security relationship in which Iraqi forces assume greater responsibility for domestic counterterrorism operations.

Why are Iranian-backed groups calling the US withdrawal a victory?

Iran has spent decades building political and military influence inside Iraq through relationships with Shi’ite parties and armed factions. Tehran has consistently argued that American military bases threaten regional sovereignty and has supported demands for the removal of US troops.

Iranian-aligned Iraqi factions have consequently portrayed September 30 as proof that sustained political and military pressure eventually forced Washington out. A commander from the Islamic Resistance in Iraq described the departure to Reuters as a historic victory for groups opposed to the US presence. That is the faction’s political interpretation rather than an independent assessment of why Washington implemented the withdrawal.

The more concrete consequence is that one military counterweight to Iranian influence disappears from Iraqi territory. How much additional influence Tehran gains will depend on Baghdad’s institutions, domestic politics and whether Iraqi armed groups comply with government attempts to bring weapons more firmly under state control.

Could Islamic State exploit the departure of American troops from Iraq?

Islamic State no longer controls major Iraqi cities or territory, but security officials say it retains dispersed sleeper cells. Kurdish commander Sirwan Barzani told Reuters that movement by such cells had increased after the withdrawal timetable became widely known, and he argued that losing US surveillance and logistical support could create opportunities for the group to regroup.

That concern does not mean Iraq’s security forces are incapable of confronting ISIS independently. Iraqi military, police and counterterrorism units have accumulated more than a decade of combat experience and possess substantially greater capability than when Islamic State swept across the country in 2014.

The uncertainty concerns specialised support. Intelligence collection, drones, surveillance and regional logistics can be difficult and expensive to replace, particularly when militants operate in remote desert or mountainous areas rather than trying to seize major cities.

How has the Iran war made the Iraq withdrawal more strategically complicated?

Iraq has occupied an unusual position by maintaining relationships with both Washington and Tehran. That balancing act has repeatedly turned Iraqi territory into a venue where the United States and Iranian-linked forces confront one another indirectly.

During the current US-Iran conflict, seven of the 18 American service members reported killed through the period covered by Reuters were serving in Iraq, including a soldier who died near Erbil during a controlled detonation of a drone in July.

Removing US troops reduces the number of American targets inside Iraq, but it can also alter Washington’s regional operating options. At the same time, Baghdad may gain more freedom to insist that armed groups stop using Iraqi territory for attacks connected to conflicts elsewhere.

What did two decades of US military involvement in Iraq ultimately cost?

More than 4,500 American troops died in the Iraq war and subsequent military operations, according to Reuters’ historical summary of the conflict. Iraqi losses were far greater, while the country experienced insurgency, sectarian violence, Islamic State’s rise and years of political instability following the 2003 invasion.

The United States withdrew once before in 2011, only for troops to return after ISIS captured a third of Iraq at its peak. That history is why September 30 is symbolically significant but does not guarantee that US forces will never again operate inside Iraq under future circumstances.

Washington is likely to maintain diplomatic, intelligence and defence relationships with Baghdad even without permanent coalition bases. The transformation is therefore from an embedded military presence toward a relationship relying more heavily on Iraqi forces and regional capabilities.

What are the key takeaways from the completion of the US military withdrawal from Iraq?

The withdrawal closes the current chapter of a US military presence that traces directly back to the 2003 invasion and the 2014 return to fight Islamic State. It is the implementation of a bilateral timetable negotiated in 2024 rather than a sudden decision triggered by one recent event.

Iranian-backed groups are celebrating the departure, while some Iraqi security figures worry about both militia influence and Islamic State sleeper cells. Neither outcome is predetermined, and much will depend on whether Iraq’s own institutions can monopolise security decision-making.

The real test begins after the final troops leave. Iraq must demonstrate that it can manage counterterrorism, militia politics and regional tensions without relying on a permanent US military presence.

What happens to US-Iraq security cooperation after the final bases close?

Training, arms sales, intelligence exchange and diplomatic coordination can continue even without large numbers of troops stationed permanently inside Iraq. Washington also retains substantial military capacity elsewhere in the Middle East, meaning withdrawal from Iraqi bases does not remove the United States from regional security.

Baghdad, however, assumes a much clearer responsibility for managing threats inside its borders. If Iraqi forces contain Islamic State and limit unauthorised militia activity, the withdrawal could reinforce sovereignty without producing the security vacuum some officials fear.

If those challenges worsen, debate over foreign support could eventually return. September 30 therefore marks the end of one long military deployment, but whether it represents the final chapter of direct American military involvement in Iraq will depend on what happens next.